Rescuers have not given up hope of finding 12 miners alive after they were trapped by flood waters at an underground coal mine in Henan Province on Monday.

New water gushed in at 300 cubic metres per hour yesterday, making rescue efforts at the Chaohua Colliery in Central China even more difficult, said officials with the State Administration of Work Safety (SAWS).

The mine, belonging to the Zhengzhou Coal Mine Group, initially flooded on Monday.

Since then, rescue teams have been attempting to locate the trapped miners. They have so far failed to find any survivors, SAWS officials said.

"Efforts will not be suspended if there is the slim hope that they are still alive," said Song Guangtai, vice-director of provincial colliery safety bureau.

After pumping out water and silt, rescuers had made their way 840 metres down the submerged shaft by Monday afternoon, Song said.

However, a Xinhua report noted Monday that rescue efforts were temporarily halted due to further flooding in the afternoon.

Rescue efforts are now in a "crucial and difficult" period as six rescue teams are working against the clock to get oxygen into the shaft.

The fate of the missing miners remains unknown, said a Zhengzhou Coal Mine Group spokesman.

Investigations are under way to establish the causes of the incident, SAWS said.

It occurred just one day after another coal mine gas explosion killed six miners who were working underground, said SAWS officials. The blast took place at a small, private colliery in Jidong County, Jixi of Northeast China's Heilongjiang Province.

At least 10 coal miners were trapped underground early on Saturday by the explosion.

Liu Shanfu, 36, a survivor, recalled that he and two other miners left the shaft at around 5 am.

They were 50 metres away from the mouth of the shaft when they heard an explosion underground and saw black smoke rising.

The blast occurred at Hada village of Jidong County when an unknown number of miners were underground.

The owner of the mine fled after the accident. Rescue work is continuing.

Henan has been the scene of several severe mining incidents in recent years due to ignorance of work safety, experts said.

For example, a gas explosion occurred on November 22 in Ruzhou city, causing the death of 22 people.

With a deposit of 100 million tons, the State-owned Chaohua coal mine had been open for about 11 years with an annual output of 2.2 million tons, according to Hu Dejin, who heads the colliery.

A local newspaper described it as a modern, fully automated operation.